Add Function Calls with a Call Stack

Add function call support to your VM in C.

Requirements:

• Define a CallFrame struct with return_address and local variables array
• Add CALL and RETURN opcodes
• Implement CALL: push a new frame, save return address, jump to function address
• Implement RETURN: pop frame, restore PC, optionally push return value
• Add a call stack (array of frames) with a maximum depth limit
• Add STORE_LOCAL idx and LOAD_LOCAL idx opcodes to access frame locals
• Write a bytecode program that computes factorial(5) recursively
• The factorial function should use JUMP_IF_FALSE for the base case, CALL for recursion, and RETURN to send results back
• Print each CALL and RETURN with the current call depth
• Show the final result of factorial(5) = 120
• Include stack overflow protection

Test:

• Show CALL pushing a new frame
• Show RETURN restoring the caller's PC
• Show call stack depth increasing and decreasing
• Show factorial(5) = 120